The process of aging deeply influences morphological and functional parameters of peripheral nerves. The observations summarized here indicate that the deterioration of myelin occurring in the peripheral nerves during aging may be explained by the fall of the levels of the major peripheral myelin proteins [e.g., glycoprotein Po (Po) and peripheral myelin protein 22 (PMP22)]. Neuroactive steroids, such as progesterone (PROG), dihydroprogesterone (5alpha-DH PROG), and tetrahydroprogesterone (3alpha,5alpha-TH PROG), are able to stimulate the low expression of these two myelin proteins present in the sciatic nerve of aged male rats. Since Po and PMP22 play an important physiological role in the maintenance of the multilamellar structure of PNS myelin, we have evaluated the effect of PROG and its neuroactive derivatives, 5alpha-DH PROG and 3alpha,5alpha-TH PROG, on the morphological alterations of myelinated fibers in the sciatic nerve of 22-24-month-old male rats. Data obtained clearly indicate that neuroactive steroids are able to reduce aging-associated morphological abnormalities of myelin and aging-associated myelin fiber loss in the sciatic nerve.

中文翻译：

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具有神经活性的类固醇会影响周围的髓鞘形成：预防或治疗年龄依赖性的周围神经功能障碍的潜在机会。

衰老过程会严重影响周围神经的形态和功能参数。此处总结的观察结果表明，衰老过程中周围神经中髓磷脂的降解可能是由于主要外周髓磷脂蛋白[例如，糖蛋白Po（Po）和外周髓磷脂蛋白22（PMP22）]的水平下降所致。具有神经活性的类固醇，例如孕酮（PROG），二氢孕酮（5alpha-DH PROG）和四氢孕酮（3alpha，5alpha-TH PROG），能够刺激老年雄性大鼠坐骨神经中这两种髓磷脂蛋白的低表达。 。由于Po和PMP22在维持PNS髓磷脂的多层结构中起着重要的生理作用，因此我们评估了PROG及其神经活性衍生物5alpha-DH PROG和3alpha的作用，5alpha-TH PROG，关于22-24月龄雄性大鼠坐骨神经髓鞘纤维的形态变化。获得的数据清楚地表明，神经活性类固醇能够减少坐骨神经中与衰老相关的髓鞘形态异常和与衰老相关的髓磷脂纤维丢失。